BAGHDAD, Iraq (CNN) --As U.S. troops continued forays into Saddam Hussein's ancestral home of Tikrit, one American soldier was killed and three wounded in an attack Monday in central Baghdad, U.S. military officials said.

The military said two of the wounded were released to their unit and the third was undergoing treatment. Earlier, witnesses said two of the soldiers were killed by what appeared to be a grenade.

The attack was the latest of almost daily guerrilla strikes against U.S. soldiers. Since President Bush declared major combat over on May 1, 49 U.S. troops have died in hostile action. A total of 247 U.S. troops have been killed since the Iraq war began in March. (Interactive: U.S. deaths)

Meanwhile, soldiers from the 4th Infantry Division searched three homes in a Tikrit neighborhood Monday and found a large arms and ammunition cache.

U.S. officials said troops are closing in on Saddam Hussein and that the raids were important in gaining intelligence on the deposed dictator and his supporters.

Saddam is changing his location every two to four hours, officials said. DNA samples will be taken from three farmhouses U.S. troops raided Sunday in Tikrit to determine whether Saddam had been there, they said.

Neighbors reportedly told 4th Division soldiers that Saddam's security chief had been in the area shortly before the farmhouse raids. No casualties were reported on either side, officials said.

"Right now he is so concerned about his survival that he is not in contact with the former regime, the Baathists, ... very often," Myers told CNN. "He is much more concerned with his own personal survival than he is with any revival of the regime. And we'll get him."

Civilians reported killed

A raid in Baghdad's upscale Mansour district Sunday turned tragic, according to witnesses and an Iraqi police officer, who said U.S. military officials briefed him.

Witnesses described U.S. commandos dressed in black cordoning off the area around a house and then opening fire on several vehicles. Three civilians were killed and four others wounded, the police officer said.

The civilians were apparently unaware the military had closed the area, the police officer said. He said U.S. military officials told him the operation targeted Saddam.

Coalition military spokesman Capt. Jeff Fitzgibbons told CNN the operation was conducted by Task Force 20, composed of special operations forces from the various branches of the armed services. But he would neither confirm nor deny the operation's target or the reports of civilian casualties.

Three separate weekend attacks killed five American troops, military officials said. Shortly before Myers arrived, soldiers attached to the 1st Marine Expeditionary Force came under grenade attack in Haswah, about 19 miles (30 kilometers) south of Baghdad. One soldier was killed and another was injured.

U.S. Central Command said three U.S. soldiers of the 4th Infantry Division guarding a hospital northeast of Baghdad died Saturday in a grenade attack. Another soldier attached to the 3rd Infantry Division was killed in an attack on a convoy in Abu Ghraib, on the outskirts of Baghdad.

Soldiers face hearing

Sources at U.S. Central Command said Monday that four military policemen accused of abusing Iraqi prisoners earlier this year will face an Article 32 hearing.

The hearing is similar to a civilian grand jury proceeding but allows the accused to see the evidence, cross-examine witnesses and present his or her own witnesses or evidence.

The soldiers are with the Pennsylvania-based 320th Military Police Battalion, an Army Reserve unit that specializes in handling prisoners of war.

The incidents allegedly took place at Camp Bucca, a complex in southern Iraq that housed thousands of Iraqi POWs.

Each soldier is charged with assault, maltreatment of prisoners and dereliction of duty. One also faces an obstruction of justice charge and the others are accused of making false statements.

Officials said the Iraqi prisoners suffered injuries as a result of the alleged abuse and were treated at the scene by military medical personnel. None of the injuries were life-threatening, officials said.